import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 26727
 * Date: 2024-09-26
 * Time: 10:25
 */
class Solution8 {
    int[] dx = {1,-1,0,0};
    int[] dy = {0,0,-1,1};
    int m;
    int n;
    boolean[][] visit;
    public int numIslands(char[][] grid) {
        m = grid.length;
        n = grid[0].length;
        visit = new boolean[m][n];
        int ret = 0;
        for(int i = 0; i < m; i++) {
            for(int j = 0; j < n; j++) {
                if(grid[i][j] == '1' && !visit[i][j]) {
                    ret++;
                    bfs(grid,i,j);
                }
            }
        }
        return ret;
    }

    public void bfs(char[][] grid, int i, int j) {
        Queue<int[]> q = new LinkedList<>();
        q.add(new int[]{i,j});
        visit[i][j] = true;

        while(!q.isEmpty()) {
            int[] t = q.poll();
            int a = t[0], b = t[1];
            for(int k = 0; k < 4; k++) {
                int x = a+dx[k], y = b+dy[k];
                if(x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == '1' && !visit[x][y]) {
                    bfs(grid,x,y);
                }
            }
        }

    }
}
